Since the advent of processes for extracting oils from seed, there are now thousands of seed oils to choose from for use in skin care. Seed oils have many properties, this is an introduction to one of these properties and the role it plays when an oil is used for cleansing (washing off) versus treatment (leave on).
Every seed in the plant kingdom can be pressed and oil extracted from it, and each oil will have a specific quality ranging from very astringent to very emollient, and everything in between.
All vegetable, fruit and seed oils (and seed butters) are combinations of these properties, which are determined by their unique Fatty Acid profile. When formulating for skincare it is important to discern if the oils you are using are more "Astringent" or more "Emollient".
ASTRINGENT OILS: rinse off
An "Astringent" is a substance which stimulates skin to contract and draw together.
Astringent oils are rich in the essential Omega 6 fatty acid (EFA) called Alpha-Linoleic acid. Oils rich in these EFAs are both deeply cleansing as well as deeply nourishing. They are lovely to the touch, with a light quality, and are easily absorbed into the skin.
Very oily skin can benefit from a cleansing oils which contains high levels of Linoleic Acid and very little Oleic acids. But care should be taken to not overly dry out the skin.
Dry skin types should also take care when choosing a cleansing oil. High levels of Linoleic Acid can cause dryness in those who have less oil producing pores and those experiencing acute dry skin (winter time, dry climate, over washing etc) and those with more mature skin (skin produces less oils as it ages).
It is plant Tannins in the oils which give them their astringent properties.
Tannins are polyphenols, powerful antioxidants manufactured by plants. It is the astringency of Tannins which causes you to pucker up when you bite into unripe fruit, and which brings cleansing properties to an oils or oil blends used to clean skin.
EMOLLIENT OILS: leave on
Treatment oils are more emollient oils or oil blends formulated to remain on the skin to be absorbed and incorporated into the skin structure.
An emollient substance nourishes, conditions, and soothes the skin helping it retain suppleness and reduce water lost from the surface of the skin. Something with emollient properties will be thicker, absorb slowly, and trap moisture. In skin care they help manage dry, itchy or scaly skin conditions.
Emollient oils help strengthen skin and increase its' resilience, helping maintaining healthy structure and function. In general, these heavier oils have higher levels of Oleic Fatty Acid. Dry skin is fragile and can be easily damaged, making it vulnerable to bacterial penetration. Bacterial penetration can then lead to itchy outbreaks and acne.
Conditioning with emollient, non drying oils is very beneficial those who skin produces less oils and those with mature or aging skin.
Cleansing oilS, need to have astringent qualities:
Astringent oils are effective in reducing sebum.
Oils high in Linoleic Acid are able to quickly penetrate pores and hair follicles where they dissolve dirt, debris and skin oils.
They are tightening, healing.
They had a drying effect on the skin and used in high amounts or left on the skin can lead to dry skin.
They have proven anti-wrinkle properties.
They can be helpful in reducing irritation and inflammation.
They are able to support healthy skin barrier functions.
When skin is deficient in Linoleic acid the sebaceous glands produce a type of sebum which is drier and firmer than healthy sebum and which can easily become stuck and form blackheads, and whiteheads and outbreaks.
An example of an oil rich in linoleic acid is Grape Seed oil. It is light, quickly absorbed, slightly astringent oil, and it is is also considered a nourishing, penetrating oil. It is not known to clog pores. It is high in Vitamin D, C, E and beta carotene, and antioxidants which can help minimize signs of aging, reduce the appearance of fine lines, maintain collagen and elastin in skin, and may help reduce under-eye circles. It has anti-inflammatory properties which can help prevent itchy breakouts. It has also been shown to stimulate skin tissue regeneration and improve wound healing. High levels of antioxidants in Grape Seed oil can help prevent clogged pores and reduce acne by regulating skin oil production. Grapeseed oil, due to its astringent nature is useful for skin toning and tightening and has been shown to minimize the prominence and size of scars. It is a good choice for sensitive skin and is known not to cause allergic reactions.
MY CLEANSING OIL BLENDS
I formulate my blends with a high amount of Linoleic fatty acid rich oils, 60-70% balanced with 30-40% oleic acid. I have found this ratio is a good fatty acid ratio for deep cleansing without being too drying and benefits most skin types, even those with occasional itchy outbreaks, sensitivities, recurring clogged pores and dry patches.
CASTOR OIL: Currently, I do not include Castor oil in my blends. Castor oil is very astringent and is known to dry out skin and cause irritation. If you have very oily skin, Castor you can add a drop or two to my cleansing blend. Those with dry skin (those who have fewer oil producing pores) and those experiencing acute dry skin issues resulting from climatic conditions, over exfoliation or use of drying skin care products, etc) should avoid the use of Castor oil in their cleansing oils. READ MORE about how to determine what is causing your dry skin issues).